Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
EVALUATION OF THE SIGMA PHASE CONTENT IN MULTI-PASS WELDING OF STAINLESS STEEL DUPLEX UNS S31803 VIA LINEAR SWEEP VOLTAMMETRY TECHNIQUE
Submission Author:
Elan Forteski , PR
Co-Authors:
Elan Forteski, Luiz Otavio Rigobello Muraro, Carolina Mocelin Gomes Pires, Maria José Jerônimo de Santana Ponte, Haroldo Ponte
Presenter: Carolina Mocelin Gomes Pires
doi://10.26678/ABCM.COBEM2021.COB2021-2083
Abstract
Duplex stainless steels are alloys with good mechanical properties and corrosion resistance due to microstructural synergy between similar volumetric fractions of ferrite and austenite. However, when these alloys are subjected to thermal or welding processes, some changes in their microstructure can occur generating deleterious intermetallic phases, such as the sigma phase. This condition can lead to important mechanical behavior depletions as loss of tenacity and pitting corrosion resistance reduction. In light of this view, the aim of the present work was to apply a new nondestructive testing, based on linear sweep voltammetry technique, to quantify the sigma phase level at welding affected zone of duplex stainless steels UNS S3180. Samples of UNS S3180 plates were submitted to MIG multi-pass welding processes. After that, the samples were transversally cutter and polished. The optical microscopy analysis detected the formation of different levels of sigma phase with increase in welding passes. It was observed that the highest level of sigma phase, for all testing samples, was observed at the outer surface of the material making feasible to apply the developed linear sweep voltammetry technique, that consists of a surface technique, to evaluate metallurgical concerns based on the contents of surface sigma phase. It was possible to detected sigma phase amounts of 0.22%, much lower than the 1.00% considered as a critical value.
Keywords
Non-destructive testing, linear sweep voltammetry, deleterious phases, corrosion
